M923 13 Speed Swap

[Crf450x]

Made some progress today. For anyone wanting to remove a cab, a front end loader on a tractor is probably not the best way. But we made it work.

 

[charlesmann]

With an 8.3 the front of the bell housing would be pretty close to the front of the cab. With the 250 it’s considerably farther back.

A note on that for anyone wanting to do this...the 8.3s have a deeper flywheel housing to accommodate the torque converter and would not allow an input shaft to make it to the pilot bearing. Nhc250 trucks have a standard depth housing and use a spacer.

Boy if they dont find a way to screw it up between models.
I wonder if machining the bell housing (if the bolt holes are deep enough) down would allow the 2 to be mated up.

Any idea how much deeper the bell housing is? Actually, how deep is a 250 housing? Ill go measure my housing.

 

[charlesmann]

Best i can measure, housing is 6.5” to the eng block.

 

[Crf450x]

Boy if they dont find a way to screw it up between models.
I wonder if machining the bell housing (if the bolt holes are deep enough) down would allow the 2 to be mated up.

Any idea how much deeper the bell housing is? Actually, how deep is a 250 housing? Ill go measure my housing.

Yep. Not a thing wrong with just using a spacer. The 250 flywheel housing is 6-1/4” deep. The spacer is 1”.
The 8.3 housing is all one piece and roughly 6-1/2” deep. Not sure on the machining part. If that didn’t work I guess you’d have to get a standard housing and build engine mounts.

 

[charlesmann]

Yep. Not a thing wrong with just using a spacer. A standard flywheel housing (nhc) is about 6” deep. The nhc spacer is an inch and the 8.3 housing is all one piece and 7” deep. Not sure on the machining part. If that didn’t work I guess you’d have to get a standard housing and build engine mounts.

then by those numbers, they are the same distance from block to aft face of housing. Unless with the spacer, its 6” total.

 

[Crf450x]

Best i can measure, housing is 6.5” to the eng block.

Ok maybe my memory got twisted somewhere. I’ll measure everything again tomorrow and edit my last post. I do know the spacer is right at an inch thick. I have an 8.3 truck I’ll be taking the trans out of when this one is done so I can get some more pictures when I do that.

 

[Crf450x]

then by those numbers, they are the same distance from block to aft face of housing. Unless with the spacer, its 6” total.

With the spacer it’s 7-1/4” total. (Going by memory, I’ll confirm these numbers tomorrow)

If you zoom in on my last picture you can barely make out the spacer.

 

[simp5782]

The NHC250 uses the same bellhousing in the 5spd 809 series trucks. Just added the spacer for the Allison in the 939.


The 6CTA do not use a spacer.

The 6cta bellhousings can have the PTO built into it in the manual transmission setup is the neat part

 

[Crf450x]

Wow. I’ve never seen a setup like that.

 

[Crf450x]

Question for you @simp5782
The coolant outlet that bolts to the engine and heads back to go to the trans cooler...can I get one of those off an m809 truck to get rid of the trans cooler? Or any small cam for that matter. If not I’ll just find a hose to work.

 

[simp5782]

Question for you @simp5782
The coolant outlet that bolts to the engine and heads back to go to the trans cooler...can I get one of those off an m809 truck to get rid of the trans cooler? Or any small cam for that matter. If not I’ll just find a hose to work.

I did a stainless pipe in the place of the heat exchanger on the NHC250 and 8.3 trucks

You can turn the hose off the outlet of the motor and then add a 90 degree pipe into a straight to Hook into the T connector pipe. Its your choice.

The setup in the pics was what we did with the aluminum radiator/intercooler setups

 

[charlesmann]

With the spacer it’s 7” total. (Going by memory, I’ll confirm these numbers tomorrow)

If you zoom in on my last picture you can barely make out the spacer.

yes sir, i can make out the spacer. well, if that swap works for you w/o a lot of major driveline modifications (xmsn to xfr case and xfr back to fwd axle), i'll try and locate 1 of those xmsns and take some measurements and make sure it'll fit in my 936A2. i truly hate automatic xmsns enough, id spend the $$$ to upgrade to a manual.

 

[Crf450x]

yes sir, i can make out the spacer. well, if that swap works for you w/o a lot of major driveline modifications (xmsn to xfr case and xfr back to fwd axle), i'll try and locate 1 of those xmsns and take some measurements and make sure it'll fit in my 936A2. i truly hate automatic xmsns enough, id spend the $$$ to upgrade to a manual.

I did some more measuring today and I was off some. I edited my last posts. Looks like you were right on the 8.3, right at 6-1/2. May be close enough to work.


Got the transmission painted today and gonna take the rest of the day off.

 

[Crf450x]

Got the Allison out today. Checked the ring gear on the flex plate against the flywheel and it’s a match. May be a standard thing, not sure, but good news regardless.

Not sure when I’ll get the 13 speed installed. Supposed to rain the next couple weeks and my yard goes to crap when it rains so can’t get the truck/tractor out.

 

[Crf450x]

There are 4 wires going to the transmission. 2 are at the shifter, I assume that’s for the neutral safety switch and I just need to connect them.

The other 2 go to what looks to be a solenoid with a fluid line going in and another line out. I’ve read that the button on the transfer case shifter is a torque converter unlock. Is that what those wires are doing?

 

[simp5782]

There are 4 wires going to the transmission. 2 are at the shifter, I assume that’s for the neutral safety switch and I just need to connect them.

The other 2 go to what looks to be a solenoid with a fluid line going in and another line out. I’ve read that the button on the transfer case shifter is a torque converter unlock. Is that what those wires are doing?

It is a 5th gear lockup. Moves the transmission to 5th fluid pressure wise so the transfer case can be shifted on the fly without lots of drive pressure

 

[Crf450x]

It is a 5th gear lockup. Moves the transmission to 5th fluid pressure wise so the transfer case can be shifted on the fly without lots of drive pressure

Awesome. Thanks.

 

[74M35A2]

The NHC250 uses the same bellhousing in the 5spd 809 series trucks. Just added the spacer for the Allison in the 939.


The 6CTA do not use a spacer.

The 6cta bellhousings can have the PTO built into it in the manual transmission setup is the neat part

That is called a rear PTO, or RPTO. Common usually on concrete mixer trucks, where they have no firewall due to rear mounted and backward facing engine.

 

[74M35A2]

Awesome write up! Keep the pics and info flowing! I’m particularly interested in the rear engine mounts to flywheel housing if you change housings, as well as U joint at trans choice, trans length, front prop shaft clearance, and trans PTO clearance once installed.

 

[Crf450x]

Awesome write up! Keep the pics and info flowing! I’m particularly interested in the rear engine mounts to flywheel housing if you change housings, as well as U joint at trans choice, trans length, front prop shaft clearance, and trans PTO clearance once installed.

Speaking of trans length, I came across this. Your transmission is 1.5” longer. Shouldn’t be a problem for you but could be an issue behind a 250.

http://www.roadranger.com/rr/ProductsServices/ProductsbyCategory/Transmissions/PCT_486870

Also, I was doing some rough measuring yesterday. The area on the fuller that sticks way out where a pto would mount lines up almost perfectly with where the Allison pto mounts and there is a place in the frame cut out for it. If not for that, I’m not sure it would fit without some frame cutting.